What happened to FNBs good service?

I was charged interest on my FNB Credit Card in October and November 2021. On 15 Nov, I requested my Private Banker to let me know why. The Private Banking Analyst came back to me to say that the credit card team is investigating. On 16 Nov, she phoned me, but gave me entirely the incorrect reasons for the interest (she clearly did not know or understand the rules of credit cards at all). I then emailed her explaining that the information she provided is not correct. On 17 Nov, she indicated that the matter was escalated to the credit card team and that it will take 3-7 working days. On 29 Nov, more than 7 working days later, I requested an update. She indicated that it was escalated to the credit card manager. On 10 Dec, I once again requested an update, more than 3 weeks after their initial 7 working days deadline. I then received an autoreply from her indicating that she is no longer a Private Banking Analyst. WHAT??? We did not receive any notice, NO communication from my Private Banker at all. What about my open query? This is absolutely ridiculous. I then escalated it to Private Clients who responded today (14 Dec) that it was once again escalated to the credit card desk. Number 1 - why do I have a Private Banker, and 2 - why is it is easy for FNB to take interest, but they are unable to tell a person why. I am formally submitting a complaint as this is absolutely the worst service I have ever received... and we are Private Clients. Not that that means anything it seems.